Hydrothermal Method And Microemulsion Method Synthesis Of Inorganic Luminescent Materials

Inorganic luminescent materials have attracted much attention due to their extensive application in many different technological areas, including biological labeling and diagnostics, light emitting diodes, photoconductive devices, optical waveguide, and lasers. At present, sulfide semiconductor and metal molybdate materials have received much attention owing to their wide application potential in many fields. Study on the size- and morphology-control synthesis is still a challenge. The development and synthesis of inorganic luminescent materials were introduced in the thesis, mainly discussing the synthesis methods such as Hydrothermal and microemulsion methods.(一)Uniform Bi2S3 fibers were synthesized via a template-free hydrothermal route using bismuth nitrate (Bi(NO3)3·5H2O), thiourea (CS(NH2)2) and lithium hydroxide (LiOH) as starting materials. The resultant powders were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescent spectra techniques (PL), respectively. It was found that Bi₂S₃ fibers could be easily synthesized in the presence of LiOH, whereas only irregular and aggregated particles were obtained without adding LiOH; and that elevating hydrothermal reaction temperature in a certain range would promote the preferred orientation growth of Bi2S3 crystallites. The PL spectra results evidenced that the optical properties of Bi2S3 crystallites were obviously influenced by their size and morphology.(二)Uniform and spherical ZnS nanoparticles with a diameter of 5–10 nm were successfully synthesized at 160℃via a facile hydrothermal process, where ZnS precursors were prepared by a microemulsion technique. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescent spectra techniques (PL), respectively. The results showed that the hydrothermal temperature exerted a more important effect than the holding time on the crystallization of ZnS crystallites. The as-prepared ZnS nanoparticles exhibited higher PL intensity than that of the normal ones of micrometer scale besides an obvious blue shift.(三)SrMoO₄ crystallites with varying morphology have been prepared by the chemical reaction of Strontium chloride and Sodium molybdate in a reverse microemulsion system consisting of water, OP (P-octyl polyethylene glycol phenylether, non-ionic surfactant), 1-pentanol (co-surfactant) and cyclohexane (oil). The resultant powders were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and photoluminescent spectra techniques (PL), respectively. It was found that SrMoO₄ crystallites with different morphologies could be synthesized by the microemulsion process with different aging times. The PL spectra results showed that the spindle-shape SrMoO4 crystallites with a higher aspect ratio resulted in better photoluminescence property.